There are 3 separate versions of the iReal Pro: one for iOS, one for Android and one for Mac.

If you purchased iReal Pro in the iOS App Store, you can install the app on your iPhone & iPad & iPod (you can't install it on your Mac computer as it is a separate app)

If you purchased iReal Pro in the Mac App Store, you can install the app on your MacBook & iMac (you can't install it on your iPhone or iPad as it is a separate app)

If you purchased iReal Pro in Google Play Store, you can install the app on your Android phone & Android tablet (you can't install it on your Mac computer or iPhone/iPad as it is a separate app)

Mac, iOS and Android are separate platforms with separate billing by Apple and Google.
Unfortunately we have no way to transfer licenses between different platforms.

When you purchase the app, the transaction is between you and Apple or Google. There is no way to transfer licenses between Apple and Google and even within Apple, there is no way to transfer purchases between the iOS App Store and the Mac App Store.
We don’t have access to their billing, we don’t have your name either and we receive limited amount of promo codes so we can't fulfill thousands of users' request who are transferring to new devices between different platforms.

Thank you for your understanding!